Uncertainty Abounds as the Gulf Leak Meter Ticks Higher

Last week, we noted that a federal panel raised the estimate of how much oil has been leaking out of the ruptured Deepwater Horizon well in the Gulf of Mexico:

Working together, U.S. government and independent scientists estimate that the most likely flow rate of oil today is between 35,000 and 60,000 barrels per day. The improved estimate is based on more and better data that is now available and that helps increase the scientific confidence in the accuracy of the estimate.

But that report left one thing unclear: Did the flow rate increase significantly after June 3, when BP cut the riser pipe in order to put the current containment dome in place? And if the flow rate did increase, by how much?

We haven’t found a clear answer to that question. An Interior Department official said that preliminary analysis suggested a modest increase, but that they didn’t have definitive information to measure the change.

And Ira Leifer, a researcher at the University of California-Santa Barbara and a member of the flow estimate panel, told us in an e-mail that the scientists can’t be sure of whether there was an increase because BP didn’t provide enough data from before the riser cut to get a good estimate of the flow then.

Given that uncertainty, we initially left the minimum flow rate in our Gulf Leak Meter at 20,000 barrels per day, reflecting what the government’s Flow Rate Technical Team reported on June 10 — an estimate they based on data from before the riser was cut.

But today, BP says it captured 16,020 barrels of oil and flared another 9,270, for a total of 25,290 barrels (1,062,180 gallons) diverted from the Gulf.

That means it’s time to update our minimum flow rate again, since BP can’t capture oil that isn’t there. The lowest possible rate you can choose is now 35,000 barrels, or 1,470,000 gallons per day, in accordance with the latest government estimate.

To help illustrate what this means, here’s a chart showing how much oil is being diverted (by siphoning or flaring), and how much is still entering the Gulf:

[ Chart is no longer available. ]

You can view or download the raw data behind this chart here or see it larger here.

We’re still looking for clarity on the question of how much cutting the riser might have increased oil flow. When we know more, we’ll update this post.

May 17: When BP releases a 30-second video of the spill, scientists began speculating that as much as 100,000 barrels of oil might be coming out of the well.

Also on May 17, BP begins siphoning oil out of the broken riser for the first time, capturing as much as 5,000 barrels per day. This effort stopped during the Top Kill operation.

May 21: A government panel, the Flow Rate Technical Team, releases a new estimate saying at least 12,000 to 19,000 barrels of oil could be coming out of the well. The assessment was based on video and satellite images.

June 3: BP cuts the broken riser pipe–possibly increasing the flow of oil–and lowers a containment dome over the wellhead.

June 4: Siphoning begins again, as BP slowly closes vents in the containment dome. Oil, gas and water are separated on the surface. A container ship stores oil, and gas is burned off, or flared. Over the next two weeks, BP increases its capture rate to around 15,000 barrels per day.

June 6: BP and Coast Guard Adm. Thad Allen report that containment efforts are now capturing around 10,000 barrels of oil a day.

June 15: A lightning strike causes a fire that shuts down siphoning temporarily. BP reports capturing 10,440 barrels of oil.

June 15: Scientists again raised the government estimate of the leak rate.

June 16: BP begins flaring oil after reaching its storage and processing capacity.

June 18: BP reports flaring 16,020 barrels of oil and flaring another 9,270, for a total of 25,290 barrels (1,062,180 gallons) diverted from the Gulf.